Static and dynamic fusimotor interaction and the possibility of multiple pace-makers operating in the cat muscle spindle

Hulliger, M.; Noth, Johannes

doi:10.1016/0006-8993(79)91092-8

Cited by 23 publications

(13 citation statements)

References 14 publications

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“…This finding supports arguments that several impulse encoders could act in the Ia terminal branches, which probably block or reset each other via antidromic invasion of all-or-none impulses (Eagles and Purple 1974). Also a combination of different encoder sites located in the diverse branches together with a second in-series encoder at the stem axon has been considered (Hulliger and Noth 1979).…”

Section: Introductionsupporting

confidence: 79%

A study of the encoder properties of muscle-spindle primary afferent fibers by a random noise disturbance of the steady stretch response

1990

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Muscle spindle stretch responses (cat gastrocnemius muscles) were studied when both steady stretch and small near-threshold random stretch determined the Ia impulse sequence. Statistical properties of the inter-impulse-intervals gave some insight into the Ia encoder mechanism. Superimposed random stretch of mean velocities sigma vel below 5 mm s-1 did not change the mean discharge rate, but the width of the Ia interspike interval distribution was clearly increased. Raising the stretch velocity further (sigma vel greater than 5 mm s-1) led to an additional increase in the distribution width, finally reaching values of 0.6 for the coefficient of variation. The shapes of the impulse interval histograms changed from symmetrical to positively skewed ones. The 1st order serial correlation coefficient of the interval sequence shifted to slightly more negative values with increasing sigma vel; on the average, the r1,2-value varied between zero and -0.2. The data were discussed in relation to current ideas on the mechanism of impulse initiation in the Ia terminal ending. They provide evidence that a combination of multiple encoder sites located in the myelinated terminal branches and a separate pathway for large static and small-amplitude dynamic stretch is not very likely. A model is proposed as to how the whole tree of myelinated axons functions as a single encoder site.

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Section: Introductionsupporting

confidence: 79%

A study of the encoder properties of muscle-spindle primary afferent fibers by a random noise disturbance of the steady stretch response

1990

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“…In such an arrangement different encoders situated on different Ia terminals would have to interact as a switching pace-maker system by competing for dominance in the final discharge pattern of the afferent axon (see Crowe and Matthews 1964b;Lennerstrand 1968b;Hulliger et al 1977c;Banks et al 1977aBanks et al , 1982Hulliger and Noth 1979;Quick et al 1980). The selection of the dominant pace-maker would then be made on the basis of the highest instantaneous rate of discharge, and this dominance would be further enhanced by antidromic invasion and resetting of the other pacemakers (Eagles and Purple 1974).…”

Section: Specificity Of Static and Dynamic Fusimotor Innervationmentioning

confidence: 99%

“…During combined stimulation of a static and a dynamic fusimotor neurone, static action may completely occlude the effect provoked by dynamic action on its own (Crowe and Matthews 1964a,b;Lennerstrand 1968b;Schafer 1974;Hulliger et al 1977b;Hulliger and Noth 1979). Formally such occlusion is another example of violation of the superposition principle.…”

Section: Non-linear Properties Of the Muscle Spindlementioning

confidence: 99%

“…Formally such occlusion is another example of violation of the superposition principle. As to the underlying receptor mechanisms, circumstantial evidence indicates that it may be a manifestation of competitive interaction of multiple pace-makers (pace-maker switching) (Crowe and Matthews 1964a;Lennerstrand 1968b;Brokensha and Westbury 1974;Hulliger et al 1977c;Hulliger and Noth 1979;Quick et al 1980). …”

Section: Non-linear Properties Of the Muscle Spindlementioning

confidence: 99%

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The mammalian muscle spindle and its central control

Hulliger

1984

Reviews of Physiology, Biochemistry and Pharmacology

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242

156

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“…With increasing stretch amplitudes a shift from nuclear bagl-fiber dominated activity to nuclear bag 2-and chain-fiber controlled activity can occur, e.g. by means of"occlusion" at the encoder sites (Hulliger and Noth 1979). Then the responses to large amplitude mechanical stimuli would reflect properties of bag2-and chainfiber mediated stretch effects.…”

Section: Discussionmentioning

confidence: 99%

Superimposing noise linearizes the responses of primary muscle spindle afferents to sinusoidal muscle stretch

1988

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Experiments were conducted in anaesthetized and spinalized cats to measure the extent to which the non-linear response of Ia afferent fibers to sinusoidal muscle stretch as expressed by the peristimulus-time-histograms, PSTHs, can be transformed into a linear one by means of the superposition of random stretch ("mechanical noise"). The gastrocnemius muscles of one hind leg were stretched and the response to sinewave muscle stretch (amplitudes between 0.01 and 4.0 mm, frequencies between 0.1 and 20 Hz) were investigated while band-limited mechanical noise was superimposed on the sinewave stretch. The random stretch upper cut-off frequency was varied between 60 and 300 Hz; the displacements were normally distributed. The noise amplitude sigma, i.e. the standard deviation of the displacement distributions, was varied systematically between 0.002 and 0.4 mm. Mechanical noise was very effective in raising the mean discharge rate. Added to the sinusoidal stretch it prevented the cessation of firing during the release phase of the stretch cycle, or at least reduced the duration of discharge pauses, i.e., a linearization occurred. In general, the larger the noise amplitude, the more the amplitude of the fundamental harmonic component was attenuated and the phase lead reduced. Apart from this rule the particular combination of superimposing small noise (sigma less than 0.02 mm) on small sinewave stretch (A less than 0.02 mm) could enhance the depth of sinusoidal modulation of cycle histograms (compared with responses to pure sinusoids). Linearizing the sinewave response by additional noise allowed the estimation of frequency response characteristics in the otherwise non-linear range of amplitudes (sinewave amplitude 0.5-1.0 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

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Static and dynamic fusimotor interaction and the possibility of multiple pace-makers operating in the cat muscle spindle

Cited by 23 publications

References 14 publications

A study of the encoder properties of muscle-spindle primary afferent fibers by a random noise disturbance of the steady stretch response

A study of the encoder properties of muscle-spindle primary afferent fibers by a random noise disturbance of the steady stretch response

The mammalian muscle spindle and its central control

Superimposing noise linearizes the responses of primary muscle spindle afferents to sinusoidal muscle stretch

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